Investigation of Lignins by FTIR Spectroscopy

Abstract

Summary: Applying special computer mathematical treatments to increase resolution of experimental spectra there were established a set of stable characteristic bands for isolated softwood lignins. In the 740–1620 cm−1 spectral range the band maximum positions did not change but values of bandwidths and peak intensities were varied in limits 15% and 32%. After analysis of the infrared spectra of 30 investigated samples a softwood lignin spectral model was constituted. This model allowed to clear discrepancies in the bands parameters of different mild isolated (lignins of Bjorkman, Pepper and Freudenberg), dioxane and technical lignin spectra. It was helpful for studying lignin structure changes during degradation procedures.

Obtaining lignin nanoparticles by sonication

“…5 and 6. Such band has been previously assigned to condensed aromatic units [23]. Furthermore, ultrasonic irradiation underwent a loss of b-O-4 linkages.…”

“…Ultrasound energy was used to increase lignin extraction yield and purity or to remove the major inorganic load from the alkali lignin with no significant modifications observed in the properties (composition, structure; at 20 kH, 100 W) of the isolated lignin samples [18][19][20] or to polymerization for high molecular weight lignin [21]. Seino et al [22] claim that the b-O-4 majority [23,24] bonds of lignin can be homolytically cleaved to some extent by sonication.…”

The Influence of Storage Conditions on the Biochemical Composition and Morphology of <i>Dahlia</i> Tubers

“…Thus, the cellulose vibrations give rise to the characteristic doublet around 1060 and 1125 cm , due to the deformation vibration of the cellulose CH and CH2 groups, respectively (Schulz and Baranska, 2007;Roman et al, 2011b). The bands around 1220 and 1240 cm -1 are due to the lignin vibrations (Derkacheva and Sukhov, 2008). Lignin is a complex polyphenolic biomacromolecule consisting of coneferyl, sinapyl and p-coumaryl alcohols, and is a major component of the cell walls (Perera et al, 2012), which provides structural and mechanical integrity of the cell walls and recalcitrance to degradation or pathogenic attacks (Perera et al, 2011).…”

Bagazo de sorgo dulce: una alternativa para la producción de etanol de segunda generación en Colombia (Parte I)

“…Si se compara el IR obtenido de la muestra podemos inferir que los picos presentes a 1596, 1505 y 1270 cm -1 corresponden a compuestos presentes en la lignina. A 1200 cm -1 se presenta un pico que representa el guaracil característico de la lignina (Derkacheva, y Sukhov, 2008).…”

“…Sin embargo, puede solaparse con un pico a 1100 cm -1 correspondiente a los enlaces éter de los CH; no obstante, la ausencia del pico a 1600 cm -1 (grupo carbonilo) permite descartar esta posibilidad. Derkacheva y Sukhov (2008) reportan que la lignina recuperada del pretratamiento alcalino de los materiales lignocelulósicos presenta un incremento en los picos de 1490 y 1188 cm -1 , cuando es analizada, los cuales son muy marcados en la Figura 5.…”